Field of the Invention
The present invention relates to a mould used in thermoplastic or thermosetting process, and more particularly to a mould with a heating device.
Related Prior Art
Conventional methods or devices for heating a mould all include the use of high frequency induction magnetic wave type heat conductive coil inside the mould or on the parting surface of the mould, and the heat conductive coil is connected to a high frequency power source to provide high frequency current to the heat conductive coil, so that the mould can be heated from room temperature to a desired temperature, and the heating is restricted in the contact surface between the mould and the material.
However, using high frequency furnace as heat device may have no safety concern, but has a relatively high cost. Besides, high frequency wave is only effective to shallow or flat mould, and unsuitable for moulds with complicated inner surface. The use of high frequency has other disadvantages: such as uneven heating, namely, uneven mould surface temperature distribution, instable induction current, long heating time, and high power consumption.
Therefore, a heating device disclosed in WO 2010/104129A1 includes: a conductive layer, an insulating layer, two electrodes and two conductive units disposed in an upper mould or a lower mould. The conductive units have a resistance coefficient smaller than a resistance coefficient of the conductive layer, which makes the surface temperature distribution of the upper or lower mould uniform. However, the conductive units are disposed at two sides of the conductive layer and are not located corresponding to the mould cavity. Therefore, in addition to the fact that the power source arrangement is inconvenient, heating current cannot be collected, and as a result, the heating effect in the mould cavity is not good.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.